Detection of silent myocardial ischaemia in asymptomatic diabetic patients during treadmill exercise testing

Diabetic patients have an increased prevalence of atherosclerosis and coronary artery disease. They may also experience higher morbidity and mortality after acute coronary syndrome compared with non-diabetic subjects.

The objective of this study was to determine the presence of silent myocardial ischaemia by treadmill test in asymptomatic diabetic patients and to compare it with age- and sex-matched subjects without diabetes mellitus.

The study design was cross-sectional and the setting was a tertiary care centre. Fifty (42 males, 8 females) asymptomatic patients with diabetes in the age group of 30-70 years were included in the study group and 30 (24 males, 6 females) non-diabetic subjects of comparable age, sex and physical activity were the control group. They were assessed for the presence of silent ischaemia by a standard treadmill test using the Bruce protocol.

Twenty-five of 50 diabetic patients showed a positive response to the exercise stress test, while 7 of 30 controls showed stress test positivity (p < 0.05). The stress test positivity showed a female predilection among diabetic patients (50% in diabetic patients and 16.67% in controls; p < 0.05). Diabetic patients with a positive stress test showed higher prevalence of hypertension (36%) and dyslipidaemia (84%) compared with diabetic patients with a negative stress test (12% and 28%, respectively) [p < 0.001]. The controls showed a better exercise capacity compared with diabetic patients; diabetic patients with a negative stress test had better exercise capacity than those with a positive stress test.

The treadmill test is a useful, specific, cost-effective, non-invasive tool for detection of silent myocardial ischaemia in asymptomatic diabetic patients.